machines- crank or dropweight

crank or dropweight

  • crank

    Votes: 38 65.5%
  • dropweight

    Votes: 20 34.5%

  • Total voters
    58

AmericanTemplar

Professional
I think that what fastdunn is saying is that since you often have to drop the arm on a dropweight multiple times, you may be "pre-stretching" inconsistently between one string and the next.
 

fastdunn

Legend

I think I do adjustment of weight once or twice or sometimes no adjustments. I just do not know how I can make this number of adjustments consistent. This makes pulling time inconistent (to make tension consistent) and inconsistent number of pulls (sorta pre-stretching effects, unintended). I just don't know how to have control over this.

By the way, I don't use drop weight any more. I use electronic now.
 

YULitle

Hall of Fame
Check the posters location, he/she does seem a little tense.

27421321987.gif


Whoa.....
 

BigGriff

Semi-Pro
I think I do adjustment of weight once or twice or sometimes no adjustments. I just do not know how I can make this number of adjustments consistent. This makes pulling time inconistent (to make tension consistent) and inconsistent number of pulls (sorta pre-stretching effects, unintended). I just don't know how to have control over this.

By the way, I don't use drop weight any more. I use electronic now.

That is a very good point. You may get a pre-stretch effect during the process of leveling the arm to horizontal. The tension may be accurate but what about the feeling of the string bed.

When a lock out/crank reaches the desired tension you don't have to repull the strings.

I guess you would have to pull each string the same number of times on a DW to keep things equal. :|

I haven't used a DW in years (don't ask) but I have shown a few of the high school players how to use their machines.
 

lethalfang

Professional
I think I do adjustment of weight once or twice or sometimes no adjustments. I just do not know how I can make this number of adjustments consistent. This makes pulling time inconistent (to make tension consistent) and inconsistent number of pulls (sorta pre-stretching effects, unintended). I just don't know how to have control over this.

By the way, I don't use drop weight any more. I use electronic now.

It doesn't matter.
The number of times you release tension does not matter at all. Theoretically speaking, what slightly matters is the total pulling time. Since it's a constant pull mechanism, the time it takes you to adjust the tension bar, is the time you are taking away from the pulling time.
In reality, if the tension bar is no longer moving after a certain amount of time (it will move at first due to "prestretching" effect), then practically the strings are in identical state.
 

1012007

Hall of Fame
Drop Wts. need to be calibrated once. I say this since I bought a calibrator and tested on my Klippermate and Eagnas Challenger I drop wts and they were both off. However, once you get a reference tension, it stays the same and doesn't need to be calibrated. Also, the Eagnas believe it or not was closer to the reading than the Klippermate.

How can you then calibrate the dropweight. I know on electrics you can but how on dropweights?
 

Loco4Tennis

Hall of Fame
here is how i made my decision:
do i have time= yes
do i have money=no
answer= i got a dropweight
ive strung 45+ frames, all mine, and it takes me 45 minutes at least to do one frame, with constant grommet issues, you can take an hour easy, but thats also true for any machine
 

YULitle

Hall of Fame
In reality, if the tension bar is no longer moving after a certain amount of time (it will move at first due to "prestretching" effect), then practically the strings are in identical state.

Are you saying that there is a static state that is reached during a constant pull? As in, a point where it is no longer applying more tension to the string because of some limitation in the string?

Because this is not true. Technically, if you left your arm tensioning a string, it would continue to elongate until either it snapped or the arm had fallen all the way to it's physical limit.
 

1012007

Hall of Fame
Technically, if you left your arm tensioning a string, it would continue to elongate until either it snapped or the arm had fallen all the way to it's physical limit.

Thats an interesting one. With a synth gut it would go all the way (eventually) but with poly... Mmmmm

BTW im not going to try it:)
 

YULitle

Hall of Fame
Thats an interesting one. With a synth gut it would go all the way (eventually) but with poly... Mmmmm

BTW im not going to try it:)

It would do it with both, though you'd have to leave it for a long time. The same would work with a CP electric. On a linear machine, it would pull until it hit the back of the track. Most machines would send the gripper back to the front at that point.
 

TenniseaWilliams

Professional
Thats an interesting one. With a synth gut it would go all the way (eventually) but with poly... Mmmmm

BTW im not going to try it:)

I have done this on my drop weight machine. When it gets near the bottom, I pull a little more string into the head. Poly's actually drop more. Natural gut drops the least. It correlates pretty well to the tension loss chart in the stringers digest.

After about 30 hours this effect becomes pretty negligible for all string types that I have tried.
 

lethalfang

Professional
Are you saying that there is a static state that is reached during a constant pull? As in, a point where it is no longer applying more tension to the string because of some limitation in the string?

Because this is not true. Technically, if you left your arm tensioning a string, it would continue to elongate until either it snapped or the arm had fallen all the way to it's physical limit.

I know what you're saying is true.
What I said was, if you're pulling one string for 15 seconds and another one for 20 seconds, the difference between the 2 strings is not noticeable.
Most of the elongation occurs in the first few seconds. What happens after that happens very very slowly. The variation of the strings themselves may be larger than the variation of pulling 15 sec vs. 20 sec.
 

TenniseaWilliams

Professional
I know what you're saying is true.
What I said was, if you're pulling one string for 15 seconds and another one for 20 seconds, the difference between the 2 strings is not noticeable.
Most of the elongation occurs in the first few seconds. What happens after that happens very very slowly. The variation of the strings themselves may be larger than the variation of pulling 15 sec vs. 20 sec.

Common sense says this is true. I have no common sense. Since I haven't actually tested this, I hate to disagree. Let's just say I would be surprised to find this accurate, even though it seems incredibly picky. 33% more time is a large component this early in the pull. If you did the entire stringbed this way, I believe you would notice.

YULitle, on your lockout machine, does it have a slow, medium, and fast pull? What is the difference in seconds between these settings? How much of an effect does this have on initial creep? I wonder how much effect on the overall creep slope? Pre-stretch has an incredible effect for the little bit of pull that goes on early in the slope.

It would be interesting to have a way to graph the creep slope objectively. With a yardstick attached to my weight arm to exaggerate any arm movement, the strings I tested for my 2 day pull had creep plateau's at 4-10 seconds (stopped obvious movement), at around 5 minutes (yardstick tip not moving if you looked really close), at 6 hours (was pretty much done, I would come back hours later and it would be slightly lower), at 30 hours (no longer moved at all and I needed the stringer). Note that this is very unscientific, all sorts of ways it (or I) could have been distorted.
 

lethalfang

Professional
The question in hand is equivalent to, if I pre-stretch the string for 15 sec. vs. 20 sec., is there going to be a noticeable difference?
In the early stages, 1 sec, 2 sec, 5 sec, can make a large difference as the string is being pulled for the first time. Once "it's already stretched," however, the elongation of the string becomes slow. You see that in a constant pull machine, the tensioner, for all practical purposes, stops moving after 10 sec.
 

YULitle

Hall of Fame
YULitle, on your lockout machine, does it have a slow, medium, and fast pull? What is the difference in seconds between these settings? How much of an effect does this have on initial creep? I wonder how much effect on the overall creep slope? Pre-stretch has an incredible effect for the little bit of pull that goes on early in the slope.

The lock-out machines are hand cranked and can be done at any speed.
 

YULitle

Hall of Fame
The question in hand is equivalent to, if I pre-stretch the string for 15 sec. vs. 20 sec., is there going to be a noticeable difference?
In the early stages, 1 sec, 2 sec, 5 sec, can make a large difference as the string is being pulled for the first time. Once "it's already stretched," however, the elongation of the string becomes slow. You see that in a constant pull machine, the tensioner, for all practical purposes, stops moving after 10 sec.

I agree. The difference between 15 and 20 seconds is not a pound, but more likely a small fraction. Most players cannot tell a 5lbs difference in reference tension OR play with dead strings long enough to render tension obsolete. So a FRACTION of a pound, is virtually nothing.
 

TenniseaWilliams

Professional
The question in hand is equivalent to, if I pre-stretch the string for 15 sec. vs. 20 sec., is there going to be a noticeable difference?
In the early stages, 1 sec, 2 sec, 5 sec, can make a large difference as the string is being pulled for the first time. Once "it's already stretched," however, the elongation of the string becomes slow. You see that in a constant pull machine, the tensioner, for all practical purposes, stops moving after 10 sec.

Pre-stretch as I know it is usually done at a very low pull weight over the entire length of the set. I would think pre-stretch timing would affect final string bed tension less than full tension timing for this reason, but hate having opinions based on intuition.

If you are saying that pre-stretching would not effect playability, I disagree.
Common sense would say there is little difference between pre-stretch and leaving the head tensioned slightly longer.

If you are saying that there is not much string creep to speak of after 10 seconds, I disagree. I agree there is not much string creep after 30 hours.

Just to make matters worse, I try to pull poly slowly, but clamp as quickly as possible. It seems like that undefinable 'poly magic' is present in greater quantities (and duration) if you don't keep the constant pull very long. Maybe I am just trying to justify a crank. (in more ways than one)
 

TenniseaWilliams

Professional
Then yes, the TF7000 had a tension head speed control.

Sorry, just had an oblique thought that somehow the speed of the pull would effect the creep while typing. Obviously not very well formed, and didn't really lead to anything unless the slow setting was over 20 seconds.
 

YULitle

Hall of Fame
Sorry, just had an oblique thought that somehow the speed of the pull would effect the creep while typing. Obviously not very well formed, and didn't really lead to anything unless the slow setting was over 20 seconds.

The speed of the pull DOES affect the creep.
 

TenniseaWilliams

Professional
I agree. The difference between 15 and 20 seconds is not a pound, but more likely a small fraction. Most players cannot tell a 5lbs difference in reference tension OR play with dead strings long enough to render tension obsolete. So a FRACTION of a pound, is virtually nothing.

It is not so much the measurable tension difference, as it is the effect on the string creep. I can't tell much of an elongation difference if I pre-stretch or not. I would assume this means I couldn't measure a tension difference, but have trouble doing this during stringing.
 

YULitle

Hall of Fame
My apologies. Lock outs are all cranks? I certainly didn't mean to imply YULitle had a speed setting. I am more used to seeing big shop machines.

speed setting.... ? I didn't catch any such implication. :)

Lock out are mostly cranks, some electrics are lock-out.
 

TenniseaWilliams

Professional
Of course there is. But that's not what I thought we were talking about.

Isn't it? If the lockout machine pulls at a certain tension for 10 seconds and then stops pulling, while a constant pull machine doesn't have any real effect after 10 seconds, wouldn't they produce the same result?
 

YULitle

Hall of Fame
Isn't it? If the lockout machine pulls at a certain tension for 10 seconds and then stops pulling, while a constant pull machine doesn't have any real effect after 10 seconds, wouldn't they produce the same result?

I can only posit that the drop-weight is pulling at a specific tension for 10 seconds while a slowly turned crank is pulling at a range of tensions (0-RT) over the same period, providing less creep adjustment.

How much longer you would have to crank depends on the string, gauge and tension.
 

TenniseaWilliams

Professional
Whoops, I think I am getting it. Lock outs (especially cranks) don't pull at a tension until the string stops elongating, then lock. They pull until they hit the reference tension and then lock?
 

TenniseaWilliams

Professional
I can only posit that the drop-weight is pulling at a specific tension for 10 seconds while a slowly turned crank is pulling at a range of tensions (0-RT) over the same period, providing less creep adjustment.

How much longer you would have to crank depends on the string, gauge and tension.

So since creep past the initial few seconds doesn't matter, pulling the clutch and re-cranking would simulate a constant pull machine?
 

TenniseaWilliams

Professional
DW IS constant pull.
I should have stated directly that I was referring to the crank lock out. Which now that I think about it, can't be the same as the DW even after the 2nd attempt, since the dwell time between the two pulls is still at a lower tension than my constant pull DW.

I think I have muddied the water. Let me start back at the beginning of my chain of thought, perhaps someone can spot were I fall off the boat.

Way back when,
So will a calibrated crank pull tension less consistently than a dropweight?

and in response

Depends on how consistently you string. If you are taking the same amount of time to move clamps after you pull tension then it should be as accurate.

and then

...
What I said was, if you're pulling one string for 15 seconds and another one for 20 seconds, the difference between the 2 strings is not noticeable.
Most of the elongation occurs in the first few seconds. What happens after that happens very very slowly. The variation of the strings themselves may be larger than the variation of pulling 15 sec vs. 20 sec.

in response

I agree 110%! :D


If you waited at least 'X' seconds, where 'X' is the end of the initial elongation (likely only around 10 seconds), would it matter how much time it took you to move the clamps?

Sorry for being so dense guys, but I did at least warn you early in the thread as to my lack of common sense... :)
 

YULitle

Hall of Fame
I misread what you said.

Yes. Pulling twice with a crank is one way to simulate a constant pull machine.
 
What are the Time frames??????????????????????????????????????????????????????????????????????????????????????????????????????????????????

between the two

Crank= ??? min

Dropweight=???min
 
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